Tandem axle suspension



Jan. 5, 1954 c. A. LINDBLOM 2,665,141

TANDEM AXLE SUSPENSION Filed Sept. 29, 1950 3 Shets-Sheet 1 1954 c. A. LINDBLOM TANDEM AXLE SUSPENSION 5 Sheets-Sheet 2 Filed Sept. 29, 1950 Jan. 5, 1954 c 2,665,141

TANDEM AXLE SUSPENSION Filed Sept. 29, 1950 3 Sheets-Sheet 3 F/Eif 0 f i (6? 58 1 1 9) 67 63 I j 64 (Q 66' w 12 Z 077 ar/0% .ZZ'IZJZ/OWZ Patented Jen. 5, 1954 TANDEM AXLE SUSPENSION Carl A. Lindblom, Auburn, Ind., assignor to International Harvester Company, a corporation of New Jersey Application September 29, 1950, Serial No. 187,507

9 Claims. (01. 280 104 .5)

This invention relates to a new and improved resilient suspension mechanism for tandem axle vehicles and more particularly to a resilient suspension system employing torsion springs arranged in a novel fashion for springing the vehicle frame from the tandem axles.

The primary object of the present invention is the provision of an improved construction and arrangement of tandem axle suspension springs by virtue of which the load is effectively equalized between the two axles. The assembly cntemplates the utilization of a relatively few number of parts having a Weight considerably less than similar structures hitherto known with the result that the pay-load capacity of the vehicle is proportionately increased.

A further object is to provide a transversely disposed, torsionally resilient mechanism on each side of the vehicle frame for springing th axle ends adjacent the related side.

Another object is to provide a torsion spring device which includes a torsion rod substantially enclosed Within a transversely disposed torsion tube.

Still another object is the provision of a torsion tube and rod spring assembly for pivotally connecting the axles to the vehicle frame without the need of heavy conventional leaf springs and thus materially decrease the weight of the suspension mechanism.

A further object is the provision of resilient, non-metallic means between the torsion tubes and the vehicle chassis and between the torsion tubes and their associated torsion ends.

The foregoing and other important objects and desirable features inherent in and encompassed by the invention together with many of the purposes and uses thereof, will become readily apparent from a reading of the ensuing description in conjunction with the annexed drawings, in which:

Fig. l is a plan view of the rear end of a chassis embodying the present invention;

Fig. 2 is a side elevational view taken substantially along the line 2-2 of Fig. 1

Fig. 3 is a rear elevational view taken substantially along the line 3-3 of Fig. 1;

Fig. 4 is a side elevational view similar to Fig. 2 showing a modified form of the invention; and

Fig. 5 is an enlarged fragmentary rear elevational view, taken generally along line 55 of Fig. l, of one side of a vehicle chassis.

Referring to the drawings, in which like reference characters designate like elements throughout thevarious views, there i shown the .rear portion of a vehicle mainframe designated generally by numeral ID. The frame it includes a pair of longitudinally extending transversely spaced side sill members II and i2 which are cross-connected by means of cross members and braces (not shown) in a conventional manner.

The rear portion of the main frame I0 is carried on a pair of transversely disposed, parallel axles or axle housings l3 and Hi. The axles i3, It in turn are supported by two sets of ground engaging wheels l5, it (one set for each axle) which are suitably mounted on the axles for rotation. It is to be understood that either one or both sets of wheels l5, [6 are capable of being drive wheels by receiving power from a differential mechanism (not shown) enclosed within differential housings ll, It. The wheels I5, I6 are secured to the opposite ends of the shafts 19,29 enclosed within the axles l3, Hi, respectively, in the usual manner and the axle shafts are driven by the differential mechanisms.

In the following description, only one side of the rear portion of the vehicle frame It) will be referred to inasmuch as both sides are provided with identical structure.

Rigidly connected to the side sill member ii approximately midway between the axles i3 and M is a supporting bracket 2|. Bracket 2! is fastened to the sill member H by a plurality of bolts 22. It will be noted that bracket 2! depends below the side sill member H and the depending portion 23 is provided with a pair of vertically alined openings 24 and 25 therethrough. A bearing member 26 in the form of a hollow cylinder projects inwardly of opening 24. Lower opening 25 is provided with a similar bearing member 21'. Bearing members 26 and 2'! may be integrally formed. on the supporting bracket 21 as shown in Fig. 3 or fastened to the bracket by any suitable means as welding or the like.

A cylindrical bushing or ring 28, formed of rubber or other non-metallic resilient material, fills the hollow cylindrical interior of the bearing member 26 and has its outer surface bonded or otherwise secured to the cylindrical interior surface of the bearing member 26. A like bushing 29 is mounted within bearing member 2'5. Both bushings 28 and 29 are provided with central openings.

Projecting through the upper opening at is a hollow torsion tube 30. Torsion tube 38 extends transversely to a point approximately midway between the side sill members I l and 12 as shown in Fig. 3. It will be apparent that only a short portion 3| of the torsion tube 39 projects outwardly of the sill member H. The interior surface of the bushing 28 is bonded or otherwise secured to the outer surface of the torsion tube 30. A lower torsion tube 32, having the same structural characteristics as the upper tube 30, is mounted in the lower bushing 29 whereby a short portion 33 extends transversely from the side sill member I I. The inwardly disposed ends 34 and 35 of the tubes and 32, respectively, are provided with internal splines 3'5, the purpose of which will be explained hereinafter.

Positioned within the upper torsion tube 30 is a coaxial torsion rod 3! having external splines 38 formed on its inner end adapted to mate with the internal splines of the tube. It will. be evident by this connection that the inner ends of the tube and rod are prevented from rotating relative to each other while their outer ends may rock relative to each other against the; torsional resistance of the tube and rod. The outer end 39 of the rod 3'! projects transversely from the short portion 3| of the tube 30'. A resilient bushing 40', similar to bushing 28, is interposed between the interior surface of the tube 30 and the exterior surface of the. rod. 31 and is secured. thereto by bonding or the like. A lower torsion rod 4! is mounted withinv the torsion tube 32 in. a like manner and has its. outer end 42. vertically spaced below the outer end 39. of torsion rod. 31.

Fastened to the outer end or short. portion 3| of the upper torsion tube 30 is a. forwardly extending arm or lever 43. The forward axle I3 has a bracket 44 secured adjacent each endthereof. Each bracket 44 has an upright ear 45. and a downwardly depending. ear 46 formed thereon. The forwardmost end 41 of the arm 43. is pivotally connected to the upright ear by means of a pin 48. The hub portion of a. lower, forwardly extending arm or lever 49.- is rigidly connected to the. outer end 33. of the lower torsion tube 32. The end 50 opposite the hub portion. is pivotally connected to the downwardly dependin ear 46 by pin 51'. Rigidly attached: adjacent. each end of the. rear axle l4 isv a bracket 51. Brackets 5| are each provided with an. upper ear '52 and a. lower ear 53. An upper rearwardly extending arm 54 has its hub. portion. connected to the outer end 39 of the upper torsionrod 31- and its opposite end pivotally attached to. the upper car 52. of bracket. 5 lby means. of pivot. pin 55. Similarly, a lower. rearwardly extending arm 56 hasone end pivotally connected to the lower ear 53. by pin, 51. and its opposite or. hub portion end rigidly connected to the. outer end 42 of the lower torsion rod...

Althoiigh the illustration of the.inventionhere-- in isv generally diagrammatic; it. is. thought that the structure. thereof will be clear to those skilled in. the art. In operation,. relative, deflection between the frame It] and the axles I13 and 1.4,, as when the vehicle is, at a. stand still andv a .load placed. thereon, isv resiliently resisted by: the. tor.- sion tube, and rod. arrangement described above. The. weight of. the. load will. cause. supporting brackets. 2 I. tamove. downwardly carrying torsion.

tubes. 30 and. 32 therewith. Inasmuch: as the forwardly extending. arms 43,and 49? have one end: rigidly connected. to. the torsion tubes 30- andv 3-2,. respectively, and their opposite ends pivotally connected. to the forward axle L3, downward movement of the. frame llltends to. rotate tor.- sion tubes. 3!! and 32. in a. clockwise direction as viewed in. Fig, 2, relative to the supporting:

attached to the torsion rods 3'! and 4|, respectively, rock in a counterclockwise direction. It will be appreciated that since the innermost end of each torsion tube is splined to the innermost end of one of torsion rods relative rotation between the ends is prevented and the outermost ends of the torsion tubes and rods rotate in opposite directions with the result that torque of the torsion tube is opposed by the torque of the torsion rod. The torsion tubes 30, 32 and rods 31 and 4| are chosen so as to be capable of twisting sufficiently to provide the necessary resilient yield between the axles l3 and I4 and the frame l0. It will also be noted that the rubber bushings interposed between the bearing members and the torsion tubes and between the torsion tubes and rod yield torsionally when the tube and rods twist relative to each other to add to the total yielding resistance afforded by the suspension arrangement.

In the event. that the wheels I5. on the axle l3 encounter uneven terrain ahead of the wheels i 6 on the axle l4}. arms 43.- and 49 will be rocked upwardly. This. movement of the arms 43, 49 will react on the rear axle 13 through the torsion tubes and rods, thus transferring. to the. rear axle. its. proportionate share of the load. The reaction. is reversed when the forward wheels [5 level out. and the rearward wheels I6 encounter the uneven spot just passed over by the forward wheels. That is. the twisting movement. of the torsion rods is opposed by an opposite twisting of the torsion tubes.

Inasmuch as the torsion tubes as well as the torsion rods. are capable of twisting the effect of connecting one end of a tube. to one end of an enclosed rod is to provide a torsion spring having a length. equal to the length of the rod and the tube. It will be appreciated that an inexpensive, compact suspension arrangement is: possible with the present. invention by eliminating. the need of costly, complex mounting members that are usually necessary for the support-of aunitary torsion spring having the same resilient characteristics of. the. suspension system constituting the present invention.

Figs. 4. and 5- represent. a modification of the above described structure. The modification is essentially the same as the suspension system hereinbefore described with the exception that the lowermosttorsiontubes and rods on each side of the vehicle are: eliminated and. in lieu thereof mounting. pins 58: (one of which is shown) are rigidly held in the. depending portions 59- of the brackets 60, which brackets are similar to bracketsv 2.1.. A lower forwardly. extending arm 61 has one end: pivotally supported on pin 58- and its opposite. end pivotally attached. to an. ear; portion 62 of. a bracket 63 rigidly connected to the. for-- ward axle. 6.4. A rearwardly. extending arm is similarly connected to mounting pin 58 and an ear portionw66i-of a'bracketth attachedrto the rear axle 68. It will beapparentthat themodified axle suspension will be less costly to: manufacture. and be adequate where the: axl loading: anticipated is. relativelysmall.

The embodiments of the invention chosen for the purposesrot illustration and description herein are those preferred as. the-result of selective tests 1 based upon requirementsfor achieving: the objects ofthe invention and developing the utility thereof in the most. desirable manner, due. regard being bad. to existing factors of economy simplicity of designand construction, production-methods andthe improvements. sought to. be: effected. It will be appreciated, therefore, that the particular structural and functional aspects emphasized herein are not intended to exclude, but rather to suggest, such other adaptations and modifications of the invention as fall within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A tandem axle vehicle suspension between a vehicle frame having parallel, transversely spaced longitudinal sill members and a tandem axle unit including transversely disposed axle housings below said frame; a bracket secured to the outer ends of each axle housing one each of said brackets having an upwardly projecting ear and a downwardly projecting car; a supporting bracket rigidly connected to each sill member having a portion depending downwardly below said frame between said axle housings, said depending portion being provided with an aperture; a pair of alined, transversely disposed torsion tubes, each tube extending through the aperture of one of said supporting brackets and having a relatively short portion projecting outwardly of the ire me and a relatively long portion extending substantially to the longitudinal median line of the frame, the inwardly disposed ends of said long portions being provided with internal splines; resilient cushioning means interposed between each of said torsion tubes and its respective supporting bracket; a torsion rod enclosed within each torsion tube having its inner end provided with external splines adapted to engage the internal splines of the tube associated therewith, said rods having their outer ends projecting from said tor sion tubes; resilient cushioning means interposed between said torsion tubes and said torsion rods; a pair of transversely spaced first upper arms, each of said arms having one end rigidly connected to the short portion of one of said torsion tubes, said arms extending in a longitudinal direc tion toward one of said axle housings; a pair of transversely spaced second upper arms, each of said arms having one end rigidly connected to the outer end of one of said torsion rods extending in a longitudinal direction opposite to that of said first upper arms toward said other axle housing; and means pivotally connecting said first upper arms to the upwardly projecting ears of the brackets secured to one axle housing and said second upper arms to the upwardly projecting ears of the brackets secured to the other axle housing.

2. The combination as set forth in claim 1 in which the depending portions of each of said supporting brackets has a lower aperture vertically spaced below said first mentioned aperture formed therein; a second pair of aligned, transversely disposed torsion tubes, each tube extending through the lower aperture of one of said supporting brackets and having a relatively short portion projecting outwardly of the frame and a relatively long portion extending substantially to the longitudinal median line of the frame, the inwardly disposed ends of said long portions being provided with internal splines; resilient cushioning means interposed between each of said second pair of torsion tubes and its respective supporting bracket; a torsion rod enclosed within each of said second pair of torsion tubes having its inner end provided with external splines adapted to engage the internal splines of the tube associated therewith, said rods having their outer ends projecting from said torsion tubes; resilient cush ioning means interposed between said second pair of torsion tubes and said torsion rods; a pair of transversely spaced first lower arms, each of said arms having one end rigidly connected to the short portion of one of said second pair of torsion tubes, said arms extending in a longitudinal direction toward one of said axlehousings; a pair of transversely spaced second lower arms, each of said arms having one end rigidly connected to the outer end of one of said second pair of torsion rods and extending in a longitudinal direction opposite to that of said first lower arms toward said other axle housing; and means pivotally connecting said first lower arms to the downwardly projecting ears of the brackets secured to one axle housing and said second lower arms to the downwardly projecting ears of the brackets secured to the other axle housing.

3. The combination as set forth in claim 1 in which the depending portions of each of said supporting brackets is provided with a mounting pin vertically spaced below said aperture; a pair of transversely spaced first lower arms, each of said arms having one end rockably supported on one of said mounting pins and its opposite end pivotally connected to one of said downwardly projecting ears of said axle housing; and a pair of transversely spaced second lower arms, each of said arms having one end rockably supported on one of said mounting pins and its opposite end pivotally connected to one of said downwardly projecting ears of said other axle housing.

4. A tandem axle vehicle suspension between a vehicle frame having parallel, transversely spaced longitudinal sill members and a tandem axle unit including transversely disposed axle housings; a supporting bracket rigidly connected to each sill member having a portion depending downwardly below said frame between said axle housings, said depending portion being provided with an aperture; a pair of alined, transversely disposed torsion tubes, each tube extending through the aperture of one of said supporting brackets; resilient cushioning means interposed between each of said torsion tubes and its respective supporting bracket; a torsion rod enclosed within each torsion tube, each of said rods having one end rigidly connected to one end of one of said torsion tubes and its opposite end projecting transversely from the other end of the torsion tube; resilient cushioning means interposed between said torsion tubes and said torsion rods: a pair of transversely spaced first arms, each of said arms having one end rigidly connected to one end of one of said torsion tubes and having its opposite end pivotally connected to one of said axle housings; and a pair of transversely spaced second arms, each of said second arms having one end rigidly connected to the transversely projecting end of one of said torsion rods and having its opposite end pivotally connected to the other of said axle housings.

5. Suspension means for a vehicle having a longitudinal frame and a pair of longitudinally spaced axles below the frame, the combination with said frame and said axles comprising a bracket secured to said frame having an aperture formed therein; a transversely disposed torsion tube extending through said aperture; resilient cushioning means interposed between said torsion tube and said bracket; a torsion rod enclosed within said torsion tube, said rod having one end rigidly connected to said torsion tube and its opposite end projecting transversely from said torsion tube; a first arm having one end rigidly connected to said torsion tube and its opaeen'nci '7 'mosite end plvotally monnected eeo" :one-sof said ules; and v=arsecond -arm EhaVing :one :end rigidly :connected :to said torsion rodandutsnpposite end -pivotally connected to z'theother of :said axles.

:6. Theicombinationiasiset eforthiniclaimfdin 'torsion itube; 1a first dower :arm having one end J :rigidly iconnected :tmsaidsecond :torsion "tube 1 and its opposite endgpivotallyccnnectedto oneofssaid axles; and {a second :10W.er :arm having zone .end :rigidly connectedtdsaid secondztorsion erod'and its .-.opposite end pivotallyconnected :to ahecother ofi-saidaxles.

7. The :structure ;applied :to :each aside :01 zthe .frame 10f r aztandem :a-xle vehicle don-springing :the fframeif-romwhe tandem axles,:.comprising :a first pair ;c.f coaxial :levers supported sfrom r-the drama for rocking movement about an :axis :generally transversely of and :below :the frame; :torsion spring means :disposed along nthe mocking axis of said :leversihavinaone end connected to;a:hub=:of one :lever :and its zother Lend connected 'to a hub .of ith-e "other lever; imeans zpivctally connecting each leverzto nnenf asaidmxles; ,a second pair of 8 scoaxialilevers:supportedirom the 'frame for rockiingzmovement about an:axis vertically spaced be- ;low and parallel to the rocking :axis of said first pairrof leverspand-means pivotally connecting one end ofieachof-saidssecondpair ofleversto an axle.

58. :The combination as set-forth in claim '7 in which second torsion spring means are disposed along the rocking axis of said second pair of levers, said second spring means having one end :connected toa hub of one of said secondpair of levers and'its'otherend connected'to ahub of the other of said second pair of ilevers.

9. The combination as set 'forthin claim 7 in which amounting pin is-disposed along the rock- *ingraxis of said-secondpair of levers, the hub of each 'of said second levers Ebeing 'pivotally connectedto said mounting pin.

CARL Al LINDBLOM.

I-References Cited in the idle of this patent UNITED STATES PATENTS Number Name Date 1,964,735 Knox et a1. July 3,1934 2,051,864 Knox e Aug. 25,1936 2,461,867 ,Avila Feb. 15, 19.49 2,480,934 Julien Sept. 6, 1949 FOREIGN PATENTS Number Country Date 225,687 Switzerland 'May 17, 1943 

